Et si le proto-bantu était aussi une langue … avec ses contraintes et ses déséquilibres

This article aims to define the phonological structure of Proto-Bantu lexical units on the basis of frequencies of reconstructed consonant co-occurrences. Starting from the main reconstructions given in BLR3, I present evidence for the presence of unexpected frequencies indicating imbalances in two directions. Certain consonant co-occurrences have not been reconstructed, essentially consonants sharing the same place of articulation and differing by only one feature, either voicing or nasality. These “gaps” in the proto-lexicon turn out to correspond to more general constraints that tend, on the one hand, towards the differentiation of place of articulation and, on the other hand, on agreement in voicing and nasality. However, in cases where *C1 and *C2 share the same place of articulation, Proto-Bantu seems to prefer identity over similarity. In looking to establish a link between the phonotactic constraints of the mother language and those of daughter languages, the latter take different directions, either a direction identical to that of the mother language, or a divergent one. In the reconstructions, the constraints on the nasality feature show similarities to those present in contemporary languages: Ganda has extended the constraint reconstructed for alveolars to all co-occurrences between a voiced stop and a nasal with the same place of articulation. However, the constraints on voicing generated by the dissimilation rule known as Dahl’s Law go in a divergent direction. I bring support here for the view that Dahl’s Law is in fact a daughter-language innovation. Furthermore, I show that this innovation was probably induced by the imbalances of the mother language; the rule fills Proto-Bantu distributional gaps. Finally, I discuss the implications of this study for the Obligatory Contour Principle (OCP).